最近在學習zookeeper,作為一個分布式協(xié)調(diào)服務(wù)全庸,它的用途挺多秀仲,服務(wù)注冊與發(fā)現(xiàn)、分布式鎖壶笼、集群選舉神僵、配置中心等。今天我先通過一個demo實現(xiàn)zookeeper的服務(wù)注冊與發(fā)現(xiàn)功能
思路
- 將產(chǎn)品服務(wù)的信息注冊到zookeeper的節(jié)點上
- 然后獲取到節(jié)點上的信息并存儲起來(本文存到List)
- Watcher機制監(jiān)控List里數(shù)據(jù)的變化并更新數(shù)據(jù) (假如產(chǎn)品服務(wù)2掛了通過監(jiān)聽機制將其移出)
-
利用輪詢或者hash等算法去獲取List里的數(shù)據(jù)供訂單服務(wù)調(diào)用(負載均衡)
注冊服務(wù)
獲取到zookeeper的實例并創(chuàng)建根節(jié)點和子節(jié)點覆劈,子節(jié)點為臨時順序節(jié)點保礼,用于保存服務(wù)對應的ip
package com.ooliuyue.product.zk;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
/**
* @Auther: ly
* @Date: 2019/4/19 11:53
*/
public class ServiceRegister {
private static final String BASE_SERVICE = "/service";
private static final String SERVICE_NAME = "/product";
public static void register(String address,int port) {
/**
* 在zk創(chuàng)建根節(jié)點path,在根節(jié)點下創(chuàng)建臨時子節(jié)點用于存放服務(wù)ip和端口
*/
try {
String path = BASE_SERVICE + SERVICE_NAME;
ZooKeeper zooKeeper = new ZooKeeper("127.0.0.1:2181",5000,(watchedEvent) -> {});
System.out.println(zooKeeper);
Thread.sleep(2000);
Stat exists = zooKeeper.exists(BASE_SERVICE + SERVICE_NAME, false);
//先判斷服務(wù)根路徑是否存在
if (exists == null){
zooKeeper.create(BASE_SERVICE + SERVICE_NAME,"".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
//將服務(wù)的ip和端口作為臨時帶序號的子節(jié)點
String server_path = address+":"+port;
zooKeeper.create(path + "/child",server_path.getBytes(),ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL);
System.out.println("product服務(wù)注冊成功");
} catch (Exception e) {
e.printStackTrace();
}
}
}
容器初始化的時候調(diào)用register(),給zk的子節(jié)點設(shè)置值(服務(wù)的url)
package com.ooliuyue.product.listen;
import com.ooliuyue.product.zk.ServiceRegister;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import java.net.InetAddress;
import java.util.Properties;
/**
* @Auther: ly
* @Date: 2019/4/19 10:43
*/
public class InitListener implements ServletContextListener {
@Override
//容器初始化的時候會調(diào)用
public void contextInitialized(ServletContextEvent sce) {
Properties properties = new Properties();
try {
properties.load(InitListener.class.getClassLoader().getResourceAsStream("application.properties"));
//獲得IP
String hostAddress = InetAddress.getLocalHost().getHostAddress();
//獲得端口
int port = Integer.valueOf(properties.getProperty("server.port"));
ServiceRegister.register(hostAddress,port);
} catch (Exception e) {
e.printStackTrace();
}
}
public void contextDestroyed(ServletContextEvent sce) {
}
}
啟動服務(wù),進行測試责语,前提需要啟動ZooKeeper
package com.ooliuyue.product.controller;
import com.ooliuyue.product.pojo.Product;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
/**
* @Auther: ly
* @Date: 2019/4/19 09:52
*/
@RequestMapping("/product")
@RestController
public class ProductController {
@RequestMapping("/get/{id}")
public Object getProduct(HttpServletRequest request, @PathVariable("id") String id){
int localPort = request.getLocalPort();
return new Product(id,"productName:" + localPort);
}
}
兩個產(chǎn)品服務(wù)啟動成功
通過工具查看節(jié)點
服務(wù)發(fā)現(xiàn)
獲取zk節(jié)點上保存的服務(wù)信息并保存到一個List中炮障,watcher機制來監(jiān)控List中數(shù)據(jù)的變化
package com.ooliuyue.order.listener;
import com.ooliuyue.order.utils.LoadBalance;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import java.util.ArrayList;
import java.util.List;
/**
* @Auther: ly
* @Date: 2019/4/19 16:26
*/
public class InitListener implements ServletContextListener {
private static final String BASE_SERVICE = "/service";
private static final String SERVICE_NAME = "/product";
private ZooKeeper zooKeeper;
private void init(){
try {
//連接zk,獲得列表信息
//watcher機制:監(jiān)控獲取到的服務(wù)列表的變化
zooKeeper = new ZooKeeper("127.0.0.1:2181",5000,(watchedEvent) -> {
if (watchedEvent.getType() == Watcher.Event.EventType.NodeChildrenChanged
&& watchedEvent.getPath().equals(BASE_SERVICE+SERVICE_NAME)) {
System.out.println("***注冊到zk的服務(wù)信息發(fā)生變化***");
updateServerList();
}
});
//第一次連接的時候要返回的列表
updateServerList();
} catch (Exception e) {
e.printStackTrace();
}
}
private void updateServerList() {
List<String> list = new ArrayList<>();
try {
List<String> children = zooKeeper.getChildren(BASE_SERVICE + SERVICE_NAME,true);
for(String subNode : children) {
byte[] data = zooKeeper.getData(BASE_SERVICE + SERVICE_NAME + "/" + subNode, false, null);
String host = new String(data,"utf-8");
list.add(host);
}
//將獲取的服務(wù)端口和IP保存List中
LoadBalance.SERVICE_LIST = list;
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void contextInitialized(ServletContextEvent sce) {
init();
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
}
}
通過實現(xiàn)一個隨機算法獲取到產(chǎn)品服務(wù),供訂單服務(wù)調(diào)用(相當于負載)
package com.ooliuyue.order.utils;
import java.util.List;
/**
* @Auther: ly
* @Date: 2019/4/22 14:00
*/
public abstract class LoadBalance {
public volatile static List<String> SERVICE_LIST;
public abstract String chooseServiceHost();
}
package com.ooliuyue.order.utils;
import org.springframework.util.CollectionUtils;
import java.util.Random;
/**
* @Auther: ly
* @Date: 2019/4/22 14:02
*/
//實現(xiàn)了一個隨機的算法(隨機獲取訂單服務(wù))
public class RandomLoadBalance extends LoadBalance {
@Override
public String chooseServiceHost() {
String result = "";
if (!CollectionUtils.isEmpty(SERVICE_LIST)) {
int nextInt = new Random().nextInt(SERVICE_LIST.size());
result = SERVICE_LIST.get(nextInt);
}
return result;
}
}
測試調(diào)用結(jié)果
package com.ooliuyue.order.controller;
import com.ooliuyue.order.pojo.Order;
import com.ooliuyue.order.utils.LoadBalance;
import com.ooliuyue.order.utils.RandomLoadBalance;
import com.ooliuyue.product.pojo.Product;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
/**
* @Auther: ly
* @Date: 2019/4/19 10:02
*/
@RequestMapping("/order")
@RestController
public class OrderController {
@Resource
private RestTemplate restTemplate;
private LoadBalance loadBalance = new RandomLoadBalance();
@RequestMapping("/get/{id}")
public Object getOrder(HttpServletRequest request, @PathVariable("id") String id){
//隨機獲取host
String host = loadBalance.chooseServiceHost();
Product product = restTemplate.getForObject("http://" + host + "/product/get/1", Product.class);
return new Order(id,"ordername",product);
}
}
發(fā)起多次請求坤候,會發(fā)現(xiàn)隨機調(diào)用其中一個服務(wù)
Watcher機制
刪除List中一個服務(wù)的信息